Professor Con Slobodchikoff of Nothern Arizona University spent 30 years studying "prairiedogese" and cracked the secret of how prairie dogs communicate with each other:

During his analysis, Slobodchikoff noticed something: Even though the human call was consistently different from the other calls, there was still significant variation between the individual human calls. He began to wonder whether the little rodents could possibly be describing their predators — not just differentiating hawk from human, but actually saying something about the particular human or coyote or hawk that was approaching.

So he devised a test. He had four (human) volunteers walk through a prairie dog village, and he dressed all the humans exactly the same — except for their shirts. Each volunteer walked through the community four times: once in a blue shirt, once in a yellow, once in green and once in gray.

He found, to his delight, that the calls broke down into groups based on the color of the volunteer's shirt. "I was astounded," says Slobodchikoff. But what astounded him even more, was that further analysis revealed that the calls also clustered based on other characteristics, like the height of the human. "Essentially they were saying, 'Here comes the tall human in the blue,' versus, 'Here comes the short human in the yellow,' " says Slobodchikoff.

Jad Abumrad and Robert Krulwich of NPR's Morning Edition have the fascinating story, including a Flash feature where you can hear the different prairie dog calls: Link